Click基础接口中是否可以为所有子命令添加全局参数？

Question

我正在使用虚拟环境下的 Click，并且在 setuptools 中使用 entry_point 指令将根映射到名为 dispatch 的函数。

我的工具公开了两个子命令 serve 和 config，我在顶级组上使用一个选项来确保用户始终传递 --path 指令。但是使用方式如下：

mycommand --path=/tmp serve

无论是serve子命令还是config子命令，都需要确保用户始终传递路径信息。理想情况下，我希望以如下方式呈现cli界面：

mycommand serve /tmp` or `mycommand config validate /tmp

当前的基于点击的实现如下：

# cli root

@click.group()
@click.option('--path', type=click.Path(writable=True))
@click.version_option(__version__)
@click.pass_context
def dispatch(ctx, path):
    """My project description"""
    ctx.obj = Project(path="config.yaml")

# serve

@dispatch.command()
@pass_project
def serve(project):
    """Starts WSGI server using the configuration"""
    print "hello"

# config

@dispatch.group()
@pass_project
def config(project):
    """Validate or initalise a configuration file"""
    pass

@config.command("validate")
@pass_project
def config_validate(project):
    """Reports on the validity of a configuration file"""
    pass

@config.command("init")
@pass_project
def config_init(project):
    """Initialises a skeleton configuration file"""
    pass

这是否可以在不向每个子命令添加路径参数的情况下实现？

- Devraj

---

你有没有找到这个问题的答案？ - larsks

没有，我当时正在使用Click 5工作，并且还没有检查过Click 6.6是否具有此选项。 - Devraj

Answer 1

如果您想将特定参数仅应用于组，但需要根据需要适用于所有命令，则可以使用一些额外的管道来完成此操作，例如：

自定义类：

import click

class GroupArgForCommands(click.Group):
    """Add special argument on group to front of command list"""

    def __init__(self, *args, **kwargs):
        super(GroupArgForCommands, self).__init__(*args, **kwargs)
        cls = GroupArgForCommands.CommandArgument

        # gather the special arguments
        self._cmd_args = {
            a.name: a for a in self.params if isinstance(a, cls)}

        # strip out the special arguments
        self.params = [a for a in self.params if not isinstance(a, cls)]

        # hook the original add_command method
        self._orig_add_command = click.Group.add_command.__get__(self)

    class CommandArgument(click.Argument):
        """class to allow us to find our special arguments"""

    @staticmethod
    def command_argument(*param_decls, **attrs):
        """turn argument type into type we can find later"""

        assert 'cls' not in attrs, "Not designed for custom arguments"
        attrs['cls'] = GroupArgForCommands.CommandArgument

        def decorator(f):
            click.argument(*param_decls, **attrs)(f)
            return f

        return decorator

    def add_command(self, cmd, name=None):

        # hook add_command for any sub groups
        if hasattr(cmd, 'add_command'):
            cmd._orig_add_command = cmd.add_command
            cmd.add_command = GroupArgForCommands.add_command.__get__(cmd)
            cmd.cmd_args = self._cmd_args

        # call original add_command
        self._orig_add_command(cmd, name)

        # if this command's callback has desired parameters add them
        import inspect
        args = inspect.signature(cmd.callback)
        for arg_name in reversed(list(args.parameters)):
            if arg_name in self._cmd_args:
                cmd.params[:] = [self._cmd_args[arg_name]] + cmd.params

使用自定义类:

要使用自定义类，将cls参数传递给click.group()装饰器，对于特殊参数，请使用@GroupArgForCommands.command_argument装饰器，并根据需要向任何命令添加与特殊参数相同名称的参数。

@click.group(cls=GroupArgForCommands)
@GroupArgForCommands.command_argument('special')
def a_group():
    """My project description"""

@a_group.command()
def a_command(special):
    """a command under the group"""

这是如何工作的？

这是因为click是一个设计良好的面向对象框架。 @click.group()装饰器通常实例化一个click.Group对象，但允许通过cls参数来覆盖此行为。 因此，相对容易继承click.Group并覆盖所需方法。

在这种情况下，我们覆盖了click.Group.add_command()，以便在添加命令时，我们可以检查命令回调参数是否与我们的特殊参数之一具有相同的名称。 如果它们匹配，则该参数将被添加到命令的参数中，就像直接进行修饰一样。

此外，GroupArgForCommands实现了一个command_argument()方法。 当添加特殊参数时，使用此方法作为装饰器，而不是使用click.argument()

测试代码：

def process_path_to_project(ctx, cmd, value):
    """param callback example to convert path to project"""
    # Use 'path' to construct a project.
    # For this example we will just annotate and pass through
    return 'converted {}'.format(value)


@click.group(cls=GroupArgForCommands)
@GroupArgForCommands.command_argument('path',
                                      callback=process_path_to_project)
def dispatch():
    """My project description"""


@dispatch.command()
def serve(path):
    """Starts WSGI server using the configuration"""
    click.echo('serve {}'.format(path))

@dispatch.group()
def config():
    """Validate or initalise a configuration file"""
    pass

@config.command("validate")
def config_validate():
    """Reports on the validity of a configuration file"""
    click.echo('config_validate')


@config.command("init")
def config_init(path):
    """Initialises a skeleton configuration file"""
    click.echo('config_init {}'.format(path))



if __name__ == "__main__":
    commands = (
        'config init a_path',
        'config init',
        'config validate a_path',
        'config validate',
        'config a_path',
        'config',
        'serve a_path',
        'serve',
        'config init --help',
        'config validate --help',
        '',
    )

    import sys, time

    time.sleep(1)
    print('Click Version: {}'.format(click.__version__))
    print('Python Version: {}'.format(sys.version))
    for command in commands:
        try:
            time.sleep(0.1)
            print('-----------')
            print('> ' + command)
            time.sleep(0.1)
            dispatch(command.split())

        except BaseException as exc:
            if str(exc) != '0' and \
                    not isinstance(exc, (click.ClickException, SystemExit)):
                raise

结果：

Click Version: 6.7
Python Version: 3.6.3 (v3.6.3:2c5fed8, Oct  3 2017, 18:11:49) [MSC v.1900 64 bit (AMD64)]
-----------
> config init a_path
config_init converted a_path
-----------
> config init
Usage: test.py config init [OPTIONS] PATH

Error: Missing argument "path".
-----------
> config validate a_path
Usage: test.py config validate [OPTIONS]

Error: Got unexpected extra argument (a_path)
-----------
> config validate
config_validate
-----------
> config a_path
Usage: test.py config [OPTIONS] COMMAND [ARGS]...

Error: No such command "a_path".
-----------
> config
Usage: test.py config [OPTIONS] COMMAND [ARGS]...

  Validate or initalise a configuration file

Options:
  --help  Show this message and exit.

Commands:
  init      Initialises a skeleton configuration file
  validate  Reports on the validity of a configuration...
-----------
> serve a_path
serve converted a_path
-----------
> serve
Usage: test.py serve [OPTIONS] PATH

Error: Missing argument "path".
-----------
> config init --help
Usage: test.py config init [OPTIONS] PATH

  Initialises a skeleton configuration file

Options:
  --help  Show this message and exit.
-----------
> config validate --help
Usage: test.py config validate [OPTIONS]

  Reports on the validity of a configuration file

Options:
  --help  Show this message and exit.
-----------
> 
Usage: test.py [OPTIONS] COMMAND [ARGS]...

  My project description

Options:
  --help  Show this message and exit.

Commands:
  config  Validate or initalise a configuration file
  serve   Starts WSGI server using the configuration

- Stephen Rauch